【树】【回溯】leetcode_113_路径总和II

【树】【回溯】leetcode_113_路径总和II

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    vector<vector<int>> pathSum(TreeNode* root, int targetSum) {
        
        vector<int> path;
        vector<vector<int>> result;
        if (root == nullptr) return result;

        path.push_back(root->val);
        traversal(root, targetSum-root->val, path, result);
        return result;

    }

    void traversal(TreeNode *cur, int count,vector<int> &path,vector<vector<int>> &result){
        if (cur->left == nullptr && cur->right == nullptr && count == 0){
            result.push_back(path);
            return;
        }

        if (cur->left){
            path.push_back(cur->left->val);
            count -= cur->left->val;
            traversal(cur->left, count, path, result);
            count += cur->left->val;
            path.pop_back();
        }
        if (cur->right){
            path.push_back(cur->right->val);
            count -= cur->right->val;
            traversal(cur->right, count, path, result);
            count += cur->right->val;
            path.pop_back();
        }

    }
};